How a Solar Electric (Photovoltaic) System Works

Graphic showing how a photovoltaic system works
System Description

The Eco Home has a 2-kilowatt solar electric system on the roof. The roof of the house was designed and built at a pitch that works well in our climate with solar technologies. In areas that don't get as much snow as we do here it is common to install solar panels flush on any roof. In snow country we cannot do that on a low pitch roof without losing several months of production when the panels are covered with snow. This system is "grid tied" with no on-site storage. The solar panels generate high voltage direct current electricity when the sun is shining and feed it into a device called an inverter in the mechanical room. The inverter changes it into 240-volt alternating current just like what the utility provides. It is fed into a breaker in the breaker panel and helps power the home's electrical loads. When the home is consuming more than the system is producing the rest is purchased as usual. If the system is producing more than is being consumed the extra is fed into the utility grid and the electrical meter records a credit. The system requires no maintenance. It simply turns on when the sun is shining and shut off at night. This system will produce, on average, over 3,100 kilowatt-hours of electricity a year which will keep over 5,600 pounds of CO2 out of the environment, by replacing some coal burning at a local power plant.

Web Content created by Wagner Zaun Architecture and Conservation Technologies under a grant from the Minnesota Pollution Control Agency 2007